Apparatus and method for selectively restricting process fluid flow in semiconductor processing

ABSTRACT

A semiconductor processing apparatus ( 10 ) is disclosed which includes a process chamber ( 12 ) and at least one substrate support ( 18 ) disposed within the process chamber ( 12 ) operable to support a substrate wafer ( 20 ). The semiconductor processing apparatus includes at least one showerhead assembly ( 14 ) disposed within the process chamber ( 12 ) facing the substrate support ( 18 ) and has a showerhead plate ( 16 ). The showerhead plate ( 16 ) has a plurality of passageways ( 17 ) extending therethrough for directing process fluid toward a substrate wafer ( 20 ) disposed on the substrate support ( 18 ). A blocking assembly ( 21 ) is disposed within the process chamber ( 12 ), the blocking assembly has an active position ( 32 ) between the showerhead assembly ( 14 ) and the substrate support ( 18 ) to restrict the flow of process fluid between the showerhead assembly ( 14 ) and the substrate support ( 18 ). The blocking assembly also has a neutral position ( 30 ) that does not restrict the flow of process fluid between the showerhead assembly ( 14 ) and the substrate support ( 18 ).

BACKGROUND OF THE INVENTION

[0001] Semiconductor fabrication typically includes depositing materialonto a semiconductor substrate wafer and etching material from thesubstrate. Often these processes take place within a process chambercontaining one or more wafers and a deposition apparatus referred to asa showerhead. The showerhead acts to direct process fluid to thesemiconductor substrate wafer. The showerhead typically includes aninlet conduit connected to a process fluid source outside of the processchamber and a showerhead plate with a number of holes extendingtherethrough to direct process fluid exiting the showerhead to thesemiconductor substrate wafer. Showerheads are also used in bothmaterial deposition and etching processes to direct deposition andetching fluid to the semiconductor substrate wafer.

[0002] Problematic edge effects often result from uneven deposition andetch across the radius of a semiconductor substrate wafer. Theseproblems often result when the characteristics of a plasma field or theflow of process fluid varies between the center of the wafer and theedge of the wafer. Such nonuniform deposition and etch often results ina semiconductor substrate wafer with disparate electrical propertiesacross its radius. Because of this disparity portions of the wafer areoften not usable for their intended function. In the case of circularwafers, inadequate deposition and etching of material adjacent to theouter edge of the wafer often renders devices formed adjacent to theouter edge of the wafer defective. As wafer diameter increases from sixinches-to eight inches-to twelve inches, the number of devices formedadjacent to the outer edge increases significantly. Therefore, edgedefects for a twelve inch wafer result in a greater number of unusabledevices as compared with a six inch wafer.

[0003] One past solution for controlling deposition and etch across theradius of a wafer was to alter the geometry of holes extending through ashowerhead plate. This technique allows process fluid to be directedtoward selected areas of the substrate wafer. Simply, to increaseprocess fluid flow to selected areas, more or larger holes are formed inthe showerhead plate opposite those areas. However, this solutionsuffers from a number of drawbacks. First, a specialized showerheadplate is typically formed for a particular process and is often notuseful for other processes. Second, experimentation with a specializedshowerhead plate is time consuming and expensive. A complete processingrun is often required to evaluate the effectiveness of a particulargeometry of holes in a showerhead plate. This consumes valuableresources and processing time. Third, the use of specialized showerheadplates for each deposition and etch process step can be costly, oftenrequiring multiple showerhead assemblies to perform multiple processingsteps and replacing showerhead assemblies to accomplish process changes.

SUMMARY OF THE INVENTION

[0004] Therefore, a need has arisen for an apparatus that canselectively control deposition and etching on the outer edge of asemiconductor substrate wafer.

[0005] A further need has arisen for an apparatus that can selectivelycontrol the deposition and etching of material across the radius of asemiconductor substrate wafer.

[0006] A further need has arisen for an apparatus that is operable toselectively vary deposition and etch edge effects in a plurality ofprocesses.

[0007] In accordance with teachings of the present invention, anapparatus and method are described which substantially eliminates orreduces disadvantages and problems associated with prior apparatuses andmethods used to deposit and etch materials during semiconductorfabrication. The apparatus includes a process chamber and a blockingassembly disposed within the process chamber. The blocking assembly maybe selectively positioned in an active or neutral position. Whenpositioned in the active position, the blocking assembly restrictsprocess fluid flow directed toward a substrate wafer from a showerheadassembly disposed in the process chamber. When positioned in the neutralposition the blocking assembly does not restrict the flow of processfluid between the showerhead assembly and the substrate wafer.

[0008] In one aspect of the present invention a semiconductor processingapparatus is disclosed. The semiconductor processing apparatus includesa process chamber and at least one substrate support disposed within theprocess chamber operable to support a substrate wafer. The semiconductorprocessing apparatus also includes at least one showerhead assemblydisposed within the process chamber that faces the substrate support andhas a showerhead plate. The showerhead plate has a plurality ofpassageways extending therethrough for directing a process fluid towarda substrate wafer disposed on the substrate support. A blocking assemblyis disposed within the process chamber. The blocking assembly has anactive position between the showerhead assembly and the substratesupport to restrict the flow of process fluid between the showerheadassembly and the substrate support. The blocking assembly also has aneutral position that does not restrict the flow of process fluidbetween the showerhead and the substrate support. More specifically, theblocking assembly includes at least one blocking disk that has an outerdiameter smaller than the outer diameter of the substrate wafer. Also,the at least one blocking disk is selectively movable between the activeposition and the neutral position.

[0009] In another aspect of the present invention a process fluidblocking assembly for controlling the flow of a process fluid in asemiconductor processing apparatus is disclosed. The process fluidblocking assembly includes a rotator selectively rotatable and at leastone blocking disk having a substantially circular configuration. Theblocking assembly also includes a linkage having a first end and asecond end. The first end of the linkage is coupled to the rotator andthe second end is coupled to the at least one blocking disk such thatthe blocking disk rotates as the rotator rotates. More specifically, theprocess fluid blocking assembly includes a plurality of blocking diskshaving multiple disk sizes where the plurality of blocking disks isoperable to releasably couple to the linkage.

[0010] In another aspect of the present invention, a method forfabricating a semiconductor device on a substrate wafer disposed in asemiconductor fabrication apparatus is disclosed. The method includessupplying process fluid to a showerhead assembly positioned opposite thesubstrate wafer. The method also includes selectively positioning ablocking assembly between the showerhead assembly and the substratewafer to restrict the flow of process fluid from the showerhead to thesubstrate wafer. This selective positioning of the blocking assemblyaffects the fabrication of the semiconductor device.

[0011] The present invention provides a number of important technicaladvantages. One technical advantage is having at least one blocking diskthat has an outer diameter smaller than the outer diameter of thesubstrate wafer. This allows the deposition apparatus to selectivelycontrol deposition on the outer edge of the substrate wafer.

[0012] Another technical advantage of the present invention is having ablocking assembly with an active position and a neutral position. Thisallows the deposition apparatus to selectively control the depositionand etching of material across the radius of a substrate wafer.

[0013] Another technical advantage of the present invention is having aplurality of blocking disks having multiple disk sizes, operable toreleasably couple to the linkage. This allows the blocking assembly toselectively vary deposition and etch edge effects in a plurality ofprocesses.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] A more complete understanding of the present embodiments andadvantages thereof may be acquired by referring to the followingdescription taken in conjunction with the accompanying drawings, inwhich like reference numbers indicate like features, and wherein:

[0015]FIG. 1 is a schematic diagram showing a cross section of asemiconductor processing apparatus incorporating teachings of thepresent invention;

[0016]FIG. 2A is a schematic diagram showing a plan view of thesemiconductor processing apparatus of FIG. 1 with a blocking assemblypositioned in a neutral position according to teachings of the presentinvention;

[0017]FIG. 2B is a schematic diagram showing a plan view of thesemiconductor processing apparatus of FIG. 1 with the blocking assemblypositioned in an active position according to teachings of the presentinvention;

[0018]FIG. 3 is a schematic cross section diagram with portions brokenaway of a semiconductor processing apparatus with a blocking assemblydepending from a top portion of the process chamber according toteachings of the present invention; and

[0019]FIG. 4 is a schematic diagram of a portion of a blocking assemblywith a heating element and electrode disposed within the blockingassembly according to teachings of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0020] Preferred embodiments and their advantages are best understood byreference to FIGS. 1 through 4, wherein like numbers are used toindicate like and corresponding parts.

[0021]FIG. 1 is a schematic diagram showing a cross section of asemiconductor processing apparatus indicated generally at 10incorporating teachings of the present invention. Semiconductorprocessing apparatus 10 includes substrate supports 18 disposed withinprocess chamber 12 operable to support substrate wafers 20.Semiconductor processing apparatus 10 also includes showerheadassemblies 14. Showerhead assemblies 14 include showerhead plates 16having a plurality of passageways 17 extending therethrough. Processfluid conduits 15 extend through process chamber 12 and are in fluidcommunication with showerhead assemblies 14 to communicate process fluidfrom the exterior of process chamber 12 into showerhead assemblies 14.

[0022] The present embodiment includes substrate supports 18, substratewafers 20, showerhead assemblies 14 and process fluid conduits 15. In analternative embodiment semiconductor processing apparatus may include asingular substrate support 18, substrate wafer 20 and showerheadassembly 14. Alternatively semiconductor processing apparatus 10 mayinclude a plurality of substrate supports 18, substrate wafers 20 andshowerhead assemblies 14.

[0023] Process fluid conduit 15 is operable to deliver process fluidsfrom a process fluid source (not expressly shown) which may beexternally located. Additionally, the process fluid source may include acontrol system for selectively controlling the flow rate of processfluid from the process fluid source to inlet conduit 15. Process fluidmay include any process fluid suitable to be delivered through ashowerhead assembly including process used in deposition processes andfluids used in etch processes.

[0024] Blocking assembly 21 is disposed within process chamber 12.Blocking assembly 21 includes rotator 22, rod assembly 24, arm assembly26 and blocking disks 28. Rotator 22 is secured within process chamber12. Rod assembly 24 is coupled to rotator 22 and extends from processchamber 12. In the present embodiment, rod assembly 24 extendssubstantially perpendicularly from process chamber 12. Arm assembly 26is coupled to rod assembly 24 and extends from rod assembly 24. Blockingdisks 28 are coupled to rod assembly 26 distal to rod assembly 24.

[0025] Rotator 22 is operable to selectively rotate. Rotator 22 may beoperated mechanically or electrically. In this embodiment rotation ofrotator 22 causes rod 24 to rotate about its longitudinal axis. In turn,rotation of rod assembly 24 causes arm assembly 26 and the disks 28attached thereto to rotate through a horizontal plane through processchamber 12 such that the rotator is operable to selectively positionblocking assembly 21 in an active position 32 (as described in FIG. 2B)and a neutral position 30 (as described in FIG. 2A).

[0026] In one embodiment rod assembly 24 may have a selectively variablelength such that the rod assembly operates to selectively raise or lowerblocking disk 28 relative to showerhead assembly 14. Rod assembly 24 mayinclude a telescoping configuration operated pneumatically,mechanically, or electrically. In an alternative embodiment, rodassembly 24 may have another configuration suitable to selectivelyshorten or lengthen rod assembly 24.

[0027] Rod assembly 24 and arm assembly 26 form linkage 19. In thisembodiment linkage 19 has a T-shaped configuration. In an alternativeembodiment linkage 19 may have any suitable configuration wherein afirst end of linkage 19 is coupled to rotator 22 and a second end oflinkage 19 is coupled to blocking disk 28. In yet another alternativeembodiment linkage 19 includes the first end coupled to rotator 22 and aplurality of ends wherein the plurality of blocking disks 28 arecoupled. In an alternative embodiment linkage 19 may have any suitableconfiguration to link blocking disk 28 to rotator 22 such that rotationof rotator 22 selectively positions blocking disk 28 in active position32 as described in FIG. 2B and in neutral position 30 as described inFIG. 2A.

[0028] In the present embodiment blocking disk 28 has an outer diametersmaller than the outer diameter of substrate wafer 20 and has a smallerdiameter than the outer diameter of shower plate 16. In the presentembodiment blocking disk 28 has a substantially circular configuration.In an alternative embodiment, blocking disk 28 may have otherconfigurations as desired to selectively restrict process fluid flowfrom showerhead assembly 14 to substrate wafer 20.

[0029] In operation process fluid is communicated through process fluidconduit 15 to showerhead assembly 14. Process fluid exits showerheadassemblies 14 through passageways 17 in showerhead plate 16. Blockingassembly 21 may then be selectively positioned in active position 32 orneutral position 30. When positioned in neutral position 30, blockingassembly 21 does not restrict the flow of process fluid from showerheadassembly 14 to blocking disk 28. When blocking assembly 21 is positionedin active position 32, blocking disk 28 acts to partially restrict theflow of process fluid exiting passageways 17 towards substrate wafer 20.Because blocking disk 28 has an outer diameter smaller than the outerdiameter of substrate wafer 20 and because active position 32 placesblocking disk 28 above the center of substrate wafer 20, the flow ofprocess fluid towards the center of substrate wafer 20 is substantiallyrestricted. The flow of process fluid to a portion of the substratewafer adjacent to the center portion of the substrate wafer issubstantially unrestricted. In one embodiment of the present inventionrod assembly 24 may be selectively shortened or lengthened such that theheight of blocking disks 28 relative to substrate wafer 20 may beselectively increased or decreased. When blocking assembly 21 is in theactive position, raising or lowering the height of blocking disk 28relative to substrate wafer 20 affects the fabrication of thesemiconductor device on substrate wafer 20.

[0030] In yet another embodiment of the present invention blocking disk28 may be releasably coupled to blocking assembly 21. In anotherembodiment of the present invention blocking assembly 21 includes aplurality of blocking disks 28 having multiple disk sizes. Thisplurality of blocking disks 28 may be releasably coupled to arm assembly26.

[0031]FIG. 2A is a schematic diagram showing a plan view of thesemiconductor processing apparatus of FIG. 1 with a blocking assembly 21positioned in a neutral position 30 according to the teachings of thepresent invention. The semiconducting processing apparatus includes aPlurality of showerhead assemblies 14 and a blocking assembly 21disposed within process chamber 12. Blocking assembly 21 includesrotator 22, rod assembly 24 coupled to rotator assembly 22, and armassembly 26 coupled to rod assembly 24. Blocking disks 28 are coupled toarm assembly 26 extending from rod assembly 24.

[0032] In the present embodiment blocking assembly 21 is positioned inneutral position 30 such that blocking disks 28 do not restrict the flowof process fluid exiting passageways 15 and directed towards substratewafers 20 (as shown in FIG. 1).

[0033]FIG. 2B is a schematic diagram showing a plan view of thesemiconductor processing apparatus of FIG. 1 with the blocking assembly21 positioned in active position 32 according to teachings of thepresent invention. When positioned in the active position 32 blockingdisks 28 are positioned to restrict the flow of process fluid exitingshowerheads 14 directed towards substrate wafers 20 (as shown in FIG.1).

[0034]FIG. 3 is a schematic diagram of a semiconductor processingapparatus 10 a with blocking assembly 21 depending from a top portion ofprocess chamber 12 according to teachings of the present invention.Substrate supports 18 support substrate wafers 20 disposed withinprocess chamber 12. Showerhead assemblies 14 including showerhead plates16 with plurality of passageways 17 extending therethrough, are disposedin process chamber 12 facing substrate supports 18. Process fluid inlets15 are in fluid communication with showerhead assemblies 14 such thatprocess fluids communicate through process fluid inlets 15 to showerheadassemblies 14 and exit showerhead assemblies 14 through passageways 17.Blocking assembly 21 is disposed within process chamber 12 such thatblocking assembly depends from a top portion of process chamber 12.Blocking assembly 21 includes rotator 22, rod assembly 24 coupled torotator 22, and arm assembly 26 coupled to rod assembly 24. Blockingdisks 28 are coupled to arm assembly 26.

[0035]FIG. 4 is a schematic diagram of a portion of a blocking assembly21 a with a heating element 36 and an electrode 40 disposed within theblocking assembly according to teachings of the present invention. Theportion of blocking assembly 21 a includes blocking disk 28 coupled toarm assembly 26. Heating element 36 is disposed within blocking disk 28a and is in electrical communication with a heating element power supply(not expressly shown) via heating element connection 38. Electrode 40 isdisposed within blocking disk 28 a. Electrode 40 is in electricalcommunication with an electrode power supply (not expressly shown) viaelectrode connection 42. In an alternative embodiment, in which blockingdisk 28 a is releasably coupled to arm assembly 26, releasableconnectors allow for the releasable connection between heating element36 and heating element connection 38 and electrode 40 and electrodeconnection 42.

[0036] In operation power from the heating element power supply may beselectively delivered to heating element 36 such that heating element 36will selectively effect the temperature within process chamber 12. Suchheating effects include altering process fluid flow and depositioncharacteristics within the chamber. Power may also be supplied from theelectrode power supply to electrode 40 via electrode connection 42 suchthat electrode 40 creates a plasma field as process fluid exitsshowerhead assembly 14. The localized plasma field effect from electrode40 may selectively effect process fluid flow and depositioncharacteristics within the process chamber 12. In an alternativeembodiment blocking assembly 21 a may include either heating element 36and heating element connection 38 or electrode 40 and electrodeconnection 42. In operation power may be supplied 42 to heating element36 such that the temperature of blocking disk 28 a increases. Power maybe supplied to heating element 36 when blocking assembly 21 a is eitherin active position 32 (as shown in FIG. 2B) or neutral position 30 (asshown in FIG. 2A).

[0037] Power may be supplied to heating element 36 while blockingassembly 21 a is in neutral position 30 for a predetermined period oruntil heating element 36 reaches a desired temperature. Blockingassembly may then be positioned in active position 32 for restrictingthe flow of process fluid exiting showerhead assembly 14. Power maycontinue to be supplied to heating element 36 or may be reduced ordiscontinued after blocking disk 28 a reaches a predeterminedtemperature. In an alternative embodiment a temperature sensor isdisposed within blocking assembly 21 a for determining the temperatureof blocking assembly 21 a.

[0038] Power may be supplied to electrode 40 when blocking assembly 21 ais either in active position 32 (as shown in FIG. 2B) or neutralposition 30 (as shown in FIG. 2A). Power may be supplied to electrode 40while blocking assembly 21 a is in neutral position 30 and then movedinto active position 32. Alternatively, power may be initially suppliedto electrode 40 when blocking assembly 40 is in active position 30.Power may continue to be supplied to electrode 40 for an entireprocessing step or may be increased, decreased or discontinued after apredetermined period.

[0039] Power may be supplied to heating element 36 and electrode 40simultaneously. Alternatively, power may be supplied to heating element36 and electrode 40 independently.

[0040] Although the disclosed embodiments have been described in detail,it should be understood that various changes, substitutions andalterations can be made to the embodiments without departing from theirspirit and scope.

What is claimed is:
 1. A semiconductor processing apparatus comprising:a process chamber; at least one substrate support disposed within theprocess chamber operable to support a substrate wafer; at least oneshowerhead assembly disposed within the process chamber facing thesubstrate support, the showerhead assembly having a showerhead plate;the showerhead plate having a plurality of passageways extendingtherethrough for directing a process fluid toward a substrate waferdisposed on the substrate support; and a blocking assembly disposedwithin the process chamber, the blocking assembly having an activeposition between the showerhead assembly and the substrate support torestrict process fluid flow from the showerhead and a neutral positionwhich allows unrestricted process flow.
 2. The apparatus of claim 1wherein the blocking assembly further comprises a rotator associatedwith the blocking assembly such that the rotator is secured within theprocess chamber, the rotator operable to selectively position theblocking assembly in its active position and its neutral position. 3.The apparatus of claim 1 wherein the blocking assembly furthercomprises: a rod assembly extending from the process chamber; an armassembly coupled to the rod assembly and extending substantiallyperpendicular from the rod assembly, at least one blocking disk coupledto the arm assembly; and a rod assembly having a selectively variablelength such that the rod assembly operates to selectively raise or lowerthe blocking disk relative to the showerhead assembly.
 4. The apparatusof claim 1 further comprising: the process chamber having a top portion;and the blocking assembly depending from the top portion.
 5. Theapparatus of claim 1 further comprising: the process chamber having abottom portion; and the blocking assembly extending from the bottomportion.
 6. The apparatus of claim 1 further comprising at least oneblocking disk releasably coupled to the blocking assembly.
 7. Theapparatus of claim 1 further comprising: a plurality of substratesupports; a plurality of showerhead assemblies disposed within theprocess chamber facing the respective substrate supports; and aplurality of blocking assemblies for selectively restricting processfluid flow from the showerhead assemblies.
 8. The apparatus of claim 1wherein the blocking assembly further comprises at least one blockingdisk having a heating element disposed within the blocking disk.
 9. Theapparatus of claim 1 wherein the blocking assembly further comprises: atleast one blocking disk having an outer diameter smaller than the outerdiameter of the substrate wafer; and the at least one blocking diskselectively movable between the active position and the neutralposition.
 10. A process fluid blocking assembly for controlling the flowof a process fluid in a semiconductor processing apparatus comprising: arotator selectively rotatable; at least one blocking disk having asubstantially circular configuration; a linkage having a first end and asecond end; and the first end coupled to the rotator and the second endcoupled to the at least one blocking disk such that the blocking diskrotates as the rotator rotates.
 11. The process fluid blocking assemblyof claim 10 further comprising: the linkage further having a pluralityof ends operable to support a plurality of blocking disks; and aplurality of blocking disks attached to the plurality of ends.
 12. Theprocess fluid blocking assembly of claim 10 further comprising therotator operable to selectively position the at least one blocking diskwithin a semiconductor processing apparatus.
 13. The process fluidblocking assembly of claim 10 further comprising: a plurality ofblocking disks having multiple disk sizes; and the plurality of blockingdisks operable to releasably couple to the linkage.
 14. The processfluid blocking assembly of claim 10 further comprising: the at least oneblocking disk having a heating element disposed within the blockingdisk; and the heating element electrically connected to a power source.15. The process fluid blocking assembly of claim 10 further comprising:the at least one blocking disk having an electrode disposed therein; andthe electrode electrically connected to a power source.
 16. A method forfabricating a semiconductor device on a substrate wafer disposed in asemiconductor fabrication apparatus comprising: supplying process fluidto a showerhead assembly positioned opposite the substrate wafer; andselectively positioning a blocking assembly between the showerheadassembly and the substrate wafer to restrict the flow of process fluidfrom the showerhead to the substrate wafer, thereby affecting thefabrication of the semiconductor device.
 17. The method of claim 16further comprising moving the blocking assembly to a positionrestricting the flow of process fluid between the showerhead assemblyand the substrate wafer.
 18. The method of claim 16 further comprisingselectively varying the height of the blocking disk between. theshowerhead assembly and the semiconductor assembly.
 19. The method ofclaim 16 further comprising selectively varying power to an electrodeforming a portion of the blocking assembly.
 20. The method of claim 16further comprising selectively varying the power supplied to a heatingelement disposed within the blocking assembly.
 21. The method of claim16 further comprising the process fluid depositing a material on thesubstrate wafer.
 22. The method of claim 16 further comprising theprocess fluid etching a portion of the substrate wafer.